Click the photos to go right to the technique description and video links. Most instructions say to cast on. They don’t tell you how to cast on and I think the assumption has always been that every knitter knows a couple of cast ons and will just use whatever they like. This is true, but it doesn’t mean that the knitter is choosing the right cast on for the knitting they will be doing.
Have you ever had a cast on that flared or one that was too tight? Yup, me too. Frustrating because you know it isn’t quite right, and usually it doesn’t block into the cast on you wish you had, despite your hopes and the assurances of others.
I think your swatch is an excellent place to try out a stitch-appropriate cast on. You can use your default cast on and, since this is a swatch, it isn’t going to make much difference. Except, then you won’t have answered the question that can make your project a true winner:
What do you need your cast on to do?
Add a design element?
I’m most often disappointed by my cast on when I wear older projects where I just always used my default cast on. I had a period where I pretty much added my trims on after I’d knit my project because I wasn’t happy with my cast on results. Let’s work together to fix this cast on problem. I’ve added videos to my techniques library for the Long-tail Cast on (if you are looking for this link it is in the Short Version) and for the double-ndl cast on.